The research is concerned with speech perception in normal adults and children and profoundly deaf children. A research theme will be perceptual learning, both in terms of development and during periods of training. Bimodal speech perception will be a focus of many of the proposed experiments. Combinations of stimulation to two out of the three senses, audition, vision, and somesthesis, will be used to examine basic constraints on bimodal speech perception as well as to evaluate schemes that may have practical significance in the design of aids for the profoundly deaf. Project I is a systematic study of candidate transformations beween voice Fo and single channel vibrotactile stimulation. Results will be incorporated in a long term evaluation of aided lipreading by hearing, "artificially deafened," young adults. Project II is a series of experiments on coding cues to segmental phonetic distinctions. Audio-visual and tactile-visual stimulus presentation will be used in a standard procedure that allows for comparison across coding schemes. Project III is concerned with normal development of speech perception between ages 3-4 years and early adolescence. Experiments will be used to study whether there is a developmental hierarchy of phonetic segmental cues. Project IV continues current work on tactile sensitivity thresholds as a function of age and stimulus waveshape. Prelingually, profoundly deaf children will be tested to determine whether vibrotactile perception is affected by auditory experience. Work on Project IV will also include development of training and testing protocols using computer graphics. Protocols will be developed to train and test children on bimodal speech perception schemes. The proposed research is particularly important for individuals whose hearing loss is such that they are unable to derive significant speech information from the auditory channel. Electric stimulation of the cochlea (implant) is gaining increasing attention as an aid for the deaf. At this time, as young children are having this expensive and traumatic implant operation, it is important that progress be made in devising wearable vibrotactile aids as a reasonable alternative.